Optionally substituted 5-methyl-6-phenyltetrahydro-1, 3, 4-oxadiazines



United States Patent Office 3,251,838 Patented May 17, 1966 3 251,838 OPTIONALLY SUBSTITUTED S-METHYL-G-PHEN- YL'IE'IRAHYDRO-1,3,4-OXADIAZINES Max 3. Kalm, Wilmette, Ill., assiguor to G. D. Searle & Co., Chicago, IlL, acorporation of Delaware N Drawing. Filed Aug. 15, 1962, Ser. No. 216,954 Claims. (Cl. 260-244) The present invention is concerned with novel oxygen and nitrogen-containing heterocyclic organic compounds and, more particularly, with optionally substituted S-methyl-6-phenyltetrahydro-1,3,4-oxadiazines of the structural formula wherein R is hydrogen, a lower alkyl, or a tertiary-amino- (lower alkylene) radical, and R is hydrogen, a lower alkyl, or aralkyl radical.

The lower alkyl radicals symbolized by the R and R terms are, typically, methyl, ethyl, propyl, butyl, pentyl, hexyl, and the branched-chain isomers thereof. Examples of lower alkylene radicals are methylene, ethylene, trimethylene, tetramethylene, pentamethylene, and the corresponding isomeric branched-chain groups. Included in the tertiary-amino(lower alkylene) radicals represented by R are, for example, dimethylaminopropyl, diethylaminoethyl, pyrrolidinopropyl, and 4-me'thylpi'peridinoethyl. The aralkyl radicals encompassed in the R term are exemplified by benzyl, phenethyl, l-methylphenethyl, phenylpropyl, phenylbutyl, phenylpentyl, and the branchedchain groups isomeric therewith.

Suitable starting materials for the manufacture of the compounds of the present invention are I I-substituted-B- hydroxy-a-methylphenethylamines of the structural formula Ho CH;

wherein R is a lower alkyl or varalkyl radical. The latter substances are converted to the corresponding N-nitroso derivatives, typically with sodium nitrite in aqueous hydrochloric acid, and reduction of those intermediates, for example with lithium aluminum hydride in a suitable solvent, produces the N-amino compounds. The latter N-amino-hydroxy compounds are allowed to react with formaldehyde, thus providing the 1,3,4-oxadiazines of the present invention, as illustrated below latter compound, resulting in d-N-amino-B-hydroxy-N,udimethylphenethylamine, which substance is allowed to react with 36% aqueous formaldehyde in aqueous solu tion to yield d-4,5-dimethyl-6-phenyltetrahydro-1,3,4-oxadiazine. By an analogous series of reactions, N-benzyl-B- hydroxy-u-methylphenethylamine is converted to 4-benzyl- 5-methyl-6-phenyltetrahydro-l,3,4-oxadiazine.

The 3-substituted compounds of the present invention are obtained from the aforementioned 3-unsubstituted compounds by reaction with a suitable alkylating agent. The reaction of 4-( 1-methylphenethyl)-5 -methyl-6-phenyltetrahydro-l,3,4 oxadiazine, for example, in benzene with methyl iodide in the presence of sodium amide as a condensing agent, at the reflux temperature, results in 3,5- dimethyl 4 (l-methylphenethyl)-6-phenyltetrahydro- 1,3,4-oxadiazine.

Hydrogenolysis of the aforementioned 4-be'nzyl-5-methyl-6-phenyltetrahydro-l,3,4-oxadiazine, suitably in the presence of a hydrogenation catalyst such as 5% palladium-on-carbon at 2-3 atmospheres of hydrogen pressure affords 5-methyl-6-phenyltetrahydro-1,3,4-oxadi3zine. On the other hand, alkylation of 4-benzyl-5-methyl-6-phenyltetrahydro-1,3,4-oxadiazine with the aforementioned alkylating agents produces the corresponding 3-substituted compounds. Hydrogenolysis of those derivatives results in the instant 3-substituted S-methyl-6-phenyltetrahydro- 1,3,4-oxadiazine, respresented by the structural formula wherein R is a lower alkyl or tertiary amino (lower alkylene) radical. As a specific example, 4-benzyl-5-methyl- 6-phenyltetrahydro-1,3,4-oxadiazine is allowed to react with methyl iodide in the presence of sodium amide to yield the corresponding 3-methyl derivative, which substance is hydrogenolyzed in the manner above described to afiord 3,5-dimethyl-G-phenyltetrahydro-1,3,4-oxadiazine.

Equivalent to the instant amines for the purposes of this invention are the corresponding non-toxic acid and quaternary salts, exemplified by the citrate, tartrate, maleate, ascorbate, gluconate, lactate, succinate, phosphate, sulfate, hydrobromide, hydrochloride, methiodide, ethiodide, methochloride, methobromide, methosulfate, etho sulfate, etc.

The compounds of the present invention display valuable pharmacological properties. They are, for example,

central nervous system-depressant, anorectic, hypocholesterolemic, and anti-inflammatory agents. In addition, they possess ulcer-inhibitory properties. They are also anti-biotic agents as is evidenced by their ability to inhibit the growth of Diplococcus pneumoniae, Escherichia colz', Bacillus subtilis, T ricophyzon mentagrophytes, and Chlorella vulgaris, and also the ability to inhibit dicotyledenous seed formation.

The invention will appear more fully from the ex amples which follow. These examples are set forth by way of illustration only, and it will be understood that the invention is 'not to be construed as limited in spirit or in scope by the details contained therein, as many modifications in materials and methods will be apparent from this disclosure to those skilled in the art. In these examples, temperatures are given in degrees centigrade C.). Quantities of materials are expressed in parts by weight unless otherwise noted.

Example 1 To a solution of 131.5 parts of l-fi-hydroxy-N,u-dimethylphenethylamine sulfate (l-epherdine sulfate) in ether.

potassium carbonate, then stripped of solvent at reduced 200 parts of water is added, dropwise with stirring at 7580, a solution of 35.2 parts of sodium nitrite in 100 parts of water over a period of about 1 /2 hours. This reaction mixture is stirred for 2'hours longer at 7580, then is cooled to room temperature and is successively extracted with benzene and ether. The combined extracts are dried over anhydrous potassium carbonate, then are stripped of solvent at reduced pressure. The residual greenish-yellow oil solidifies on standing to afford d-fi-hydroxy-N,u'- dimethyl N nitrosophenethylamine, melting at about 82-89 and characterized further by an optical rotation of +68 in methanol.

A suspension of 79 parts of lithium aluminum hydride in 2800 parts of anhydrous ether is heated at the reflux temperature with stirring for about 45 minutes, at the end of which time the heat source is removed and a solution of 202 parts of d-fi-hydroxy-N,a-dimethyl-N-nitrosophenethylamine in 440 parts of benzene containing 700 parts of ether is added dropwise with stirring. After the addition is complete, the reaction mixture is heated at the reflux temperature with stirring for about 5 hours, then is cooled to 05 and is treated successively with 83 parts of water, 62.5 parts byvolume of aqueous sodium hydroxide, and 291 parts of water. The precipitated inorganic salts are removed by filtration, and the filtrate is concentrated to dryness at reduced pressure to afford a residual yellow oil. Distillation of this yellow oil at reduced pressure affords pure d-N- amino-,B-hydroxy-N,a-dimethylphenethylamine, boiling at 117-1l8 at 0.65 mm. pressure. It is characterized further by an optical rotation in methanol, varying between +20.5 and +245".

To a solution of 26.3 parts of d-N-amino-fl-hydroxy- N,u-dimethylphenethylamine in 100 parts of Water is added 12.8 parts by volume of 36% aqueous formaldehyde, and the resulting reaction mixture is shaken vigorously for about 15 minutes, then is extracted with The ether extracts are dried over anhydrous pressure, resulting in a residual greenish oil. This oil is distilled at reduced pressure to yield colorless d-4,5-dimethyl-6-phenyltetrahydro-l,3,4 oxadiazine, boiling at 102103% at 0.7 mm. pressure. It is characterized further by an optical rotation of +65 in chloroform, a refractive index of 1.5450 at and by the structural formula NH 0113- N (3H3 Example 2 To a suspension of 3.12 parts of sodium amide in 176 parts of dry benzene is added a solution of 7.68 parts of d-4,5 dimethyl-6-phenyltetrahydro-1,3,4-oxadiazine in 44 parts of dry benzene. The resulting reaction mixture is heated with stirring at the reflux temperature for about minutes at the end of which time the heat source is removed, and a solution of 8.51 parts of methyl iodide in 44 parts of dry benzene is added dropwise over a period of about 10 minutes. An exothermic reaction occurs during the addition and a precipitate forms toward the end of that addition. Heating at the reflux temperature is continued with stirring for about 3 hours, after which time the mixture is cooled in an ice bath and diluted by the cautious addition of 75 parts of water. The benzene layer is separated and washed with water, dried over anhydrous potassium carbonate, then stripped of solvent at reduced pressure. Distillation at reduced pressure affords pure d-3,4,5-trimethyl-6-phenyltetrahydro-1,3,4-oxadiazine, boiling at 8587 at 0.75 mm. It is characterized further by an optical rotation of t 4 r '+34.5 in methanol, by a refractive index of 1.5191 at 25, and also by the structural formula.

l-C Ha Example 3 The substitution of 8.14 parts of 2-diethylarninoethyl.

chloride in the procedure of Example 2 results in d-3-(2- diethylaminoethyl) -4,5-dimethyl-6-phenyltetrahydro-1,3,4- oxadiazine, boiling at 127-128 at 0.5 mm. pressure. It displays an optical rotation of +19 in methanol and a refractive index of 1.5053 at 25". This substance is represented by the structural formula C HzC H;

0 HP /NC mourn onto H, C H; Example 4 By substituting 9.69 parts of 2-(4 methylpiperidino) ethyl chloride and otherwise proceeding according to the processes of Example 2, d-3-[2-(4-methylpiperidino)eth- 'yl] -4,5-dimethyl-6-phenyltetrahydro 1,3,4 oxadiazine is obtained. It is characterized by a boiling point of 132 at.

0.24 mm. pressure, by an optical rotation of in methanol, and by a refractive index of 1.5160 at 25,". It is represented by the structural formula Q 0 V W V CE: N-OH C am on,

Example 5 By substituting 7.22 parts of n-hexyl chloride and otherwise proceeding according to the processes described in Example 2, d'-3-n-hexyl-4,5-dimethyl-6-phenyltetrahydro- 1,3,4-oxadiazine of the structural formula is obtained.

Example 6 The substitution of 7.3 parts of 3-dimethyla-minopropyl chloride in the procedure of Example 3 results in d-3-(3- dimethy-larninopropyl)-4,5-dimethyl-6-phenyltetrahydro-1,

3,4-oxadiazine of the structural formula V By substituting 9.69parts of 3-piperidinopropyl chloride and otherwise proceeding according to the processes of Example 4, d-3-(3-piperidinopropyl)-4,5-dimethyl-6- phenyltetrahydro-l,3,4-oxadiazine is obtained. It is represented by the structural formula C l N-C mo HtornN E; f

Example 8 i 11' CH CHN 2 2 CH3 N Example 9 The substitution of 9.69 parts of 2-(2-ethylpyrrolidino) ethyl chloride in the procedure of Example 4 results in d- 3-[2-(2-ethylpyrrolidino)ethyl]-4,5-dimethyl-6- phenyltetrahydro-1,3,4-oxadiazine of the structural formula Q L N-CHgCHzN Example To a suspension of 119 parts of N-benzyl-B-hydroxy-mmethylphenethylamine (N-benzylnorephedrine) in 450 parts of water is added 49 parts of concentrated hydrochloric acid, and the resulting mixture is heated to 75 in order to effect solution. To this solution, at 75-80", is added over a period of about 1% hours with stirring, a solution of 34.5 parts of sodium nitrite in 100 parts of water. Stirring at 75-80 is continued for about 2 hours longer, after which time the reaction mixture is cooled and extracted with benzene. The organic layer is separated, dried over anhydrous potassium carbonate, decolorized with activated carbon and stripped of solvent at reduced pressure to afford a residual orange-colored oil. This oily product crystallizes on standing to yield 'N-benzyl-fi-hydroxy-a-methyl N nitrosophenethylamine as a low-melting solid.

A suspension of 14.07 parts of lithium aluminum hydride in 700 parts of anhydrous ether is heated at reflux for about 1% hours, at the end of which time a solution of 50 parts of N-benzyl-,8-hydroxy'a-methyl-N- nitrosophenethylamine in 210 parts of anhydrous ether is added dropwise over a period of about 2 hours. Heating at the reflux temperature is continued with stirring for about 5 hours, at which point the excess reagent is destroyed by the addition of 9.8 parts of ethyl acetate while the mixture is cooledin an ice bath. To this mixture is then added successively 14.8 parts of water, 11.1 parts of aqueous sodium hydroxide, and 51.8 parts of water. The resulting precipitated solids are removed by filtration, and the filtrate is stripped of solvent at reduced pressure. The residual product is distilled at reduced pressure to afford N-amino-N-benzyl-jS-hydroxy-a-methylphenethylamine, boiling at l77l80 at 0.9 mm. pressure.

The latter free base is converted to the corresponding hydrochlorideby dissolution in absolute ethanol followed by acidification of the resulting solution with isopropanolic hydrogen chloride and dilution of the mixture with anhydrous ether. The crystalline precipitate is recrystallized from ethanol-ether to afiord N-amino-N- benzyl-fi-hydroxy-a-methylphenethylamine hydrochloride, melting at about 146-150- (dec.).

To a suspension of 19.5 parts of N-amino-N-benzyl-B- hydroxy-a-rnethylphenethylamine in 60 parts of water is added 6.68 parts by volume of 36% aqueous formaldehyde, and this reaction mixture is shaken vigorously for about 10 minutes. Extraction of the mixture first with then stripped of solvent and finally is distilled at reduced pressure to afford pure 4-benzyl-5-methyl-6-phenyltetra hydro-1,3,4-oxadiazine, which boils at l63166 at 0.75 mm. pressure and is characterized further by the structural formula NH v CH3 N To a solution of the latter free base in absolute ethanol is added isopropanolic hydrogen chloride, and this acidic mixture is then diluted with anhydrous ether to the point of turbidity. filtration and recrystallized from ethanolether to yield crystalline 4-benzyl-5-methyl 6phenyltetrahydro 1,3,4- oxadiazine hydrochloride, which substance melts at about 142-144 (dec.).

7 Example 11 The reaction of 10.72 pants of 4-benzyl-5-rmethyl-6- phenyltetrahydro-l,3,4-oxadiazine with 7.22 parts of nhexyl chloride by the procedure described in Example 2 results in 4-benzyl-3 -n-hexyl-5-methy l-6-.phenyltetra1hydro- 1,3,4aox-adiazin of the structural formula Example 12 stirringfor about 2% hours longer, then is cooled to room temperature. The aqueous layer .is removed by decantation and the residual oil is extracted into benzene. Further dilution of the aqueous. phase with water, and extraction with benzene afiords an organic solution which is combined with the original extract, then is washed with water, and dried over anhydrous potassium carbonate. Distillation of the solvent at reduced pressure atlonds a viscous yellow oil, which is N-(l-methylphenethyl) -,B-hydroxy-u-methyl-N-nitrosophenethylamine.

To a suspension of-59.2 parts of lithium aluminum hydride in 1750 parts of anhydrous ether, heated at the reflux temperature for about one hour, is added over .a period of about 2 hours, a solution of 232.3 parts of N (l methylphenethyl) [3 hydroxy a methyl-N- nitrosophenethylamine in 220 parts of benzene containing 350 parts of ether. This mixture is heated at the reflux tempertaure with stirring for about 5 hours longer, is

then stored at room temperature for about 16 hours, and

is finally heated at reflux for an additional 4 hours. The excess reagent is destroyed by the addition, at ice-bath temperature, of 45 parts of ethyl acetate. To that mixture is then added successively 62.5 parts of water, 46.8 parts of 20% aqueous sodium hydroxide, and 218 parts of water. Stirring is continued at room temperature for about one hour, after which time the mixture is filtered. Distillation of the solvent from the filtrate at reduced pressure affords a residual yellow oil which solidifies on standing. Recrystallization from hexane affords pure N amino N (1 methylphenethyl) ,8 hydroxy-umethylphenethylamine.

The resulting precipitate is collected by To a suspension of 205.9 parts of N-amino-N-(lmethylphenemethyl) 3 hydroxy a methylphenethylamine in 1000 parts of water is added 64 parts of 36% aqueous formaldehyde, and the resulting reaction mixture is stirred at room temperature for about 2 hours. This mixture is then stirred with a large volume of chloroform, and the organic layer is separated. The aqueous layer is extracted with chloroform, and the chloroform extracts are combined, dried over anhydrous potassium carbonate, and stripped of solvent at reduced pressure to afford 4 (1 methylphenethyl) methyl 6 phenyltetraw hydro-1,3,4-oxadiazine as an orange oil.

To a solution of the latter free base in anhydrous ether is added isopropanolic hydrogen chloride until the mixture is slightly acidic. The solvent is decanted from the precipitated oil, which is recrystalized from absolute ethanol-anhydrous ether to afford white needles of 4-(1- methylphenethyl) 5 methyl 6 phenyltetrahydro- 1,3,4-oxadiazine hydrochloride, melting at about 196.5-

A suspension of 6.48 parts of 4-(l-methylphenethyl)-5- 'methyl-6-phenyltetrahydro-1,3,4 oxadiazine hydrochloride in water is made alkaline by the addition of 6 N aqueous sodium hydroxide, and the free base which separates is extracted into ether. The ether extract is dried over anhydrous potassium carbonate, then is stripped of solvent at reduced pressure, and the residual colorless oil is dissolved in about 88 parts of benzene. This benzene solution is concentrated to about /2 volume in order to remove the moisture, then is added to a suspension of 1.52 parts of sodium amide in 176 parts of dry benzene. This reaction mixture is heated at the reflux temperature, with stirring, for about 30 minutes, at the end of which time the heat source is removed and a solution of 4.16 parts of methyl iodide in 44 parts of dry benzene is added dropwise. Heating at the reflux temperature with stirring is continued for about 3 hours longer, after which time the mixture is cooled in an ice bath and is diluted with about 75 parts of water. The aqueous phase is separated and extracted with benzene, and the combined benzene extracts are dried over anhydrous potassium carbonate, then are stripped of solvent at reduced pressure to afiord, as an oil, 4'-(l-methylphenethyl)-3,5-dimethyl- 6-phenyltetrahydro-1,3,4-oxadiazine.

A solution of the latter free base in absolute ethanol is made acidic by the addition of isopropanolic hydrogen chloride, and the productis precipitated by the addition N-CH Hot 0113iN/ tHHeQ Example 14 By substituting 152.5 parts of dl-N-n-butyl-B-hydroxy- (it-methylphenethylamine sulfate and otherwise proceeding according to the processes of Example 1, dl-4-n-buty1-5- This substance is represented by methyl-6-phenyltetrahydro-1,3,4-oxadiazine of the, structural formula CH2CH2CH2CH3 is obtained.

Example 15 T he substitution of 131.5 parts of dl-fi-hydroxy-N,a-dimethylphenethylamine sulfate in the procedure of Example 1 results in dl-4,5-dimethyl-6-phenyltetrahydro-1,3,4? oxadiazine of the structural formula What is claimed is: 1. A compound of the formula NR I OH;

wherein R is selected from the group consisting of hydrogen and radicals of the class consisting of lower alkyl, di- (lower alkyl) amino (lower alkylene),

Alk-N c n1)n and Alk-N Hz) in (lower alkyl) and R is selected from the group consisting of lower alkyl and phenyl(lower alkylene).

2. d-4,5-dimethyl-6-phenyltetrahydro-1,3,4-oxadiazine.

3. d 3,4,5 trimethyl-6-phenyltetrahydro-1,3,4-oxadiazme.

Y 4. d 3 (Z-diethylaminoethyl)-4,5-dimethyl-6-phenyltetrahydro-1,3,4-0xadiazine.

5. d 3 [2-(4-methylpiperidino)ethyl]-4,5-dimethyl- 6-phenyltetrahydro-1,3,4-oxadiazine. 6. A compound of the formula lit-Q wherein Alk is lower alkylene.

7. 4 (1 methylphenethyl)-5-methyl-6-phenyltetrahydro-l,3,4-oxadiazine.

8. 4 benzyl-S-methyl-6-phenyltetrahydro-1,3,4-oxadiazine. I

'9. A compound of the formula wherein Alk is lower alkylene.

10. 3,5 dimethyl 4-(l-methylphenethyl)-6-pheny1 tetrahydro-1,3,4-oxadiazine.

9 11. A compound of the formula OH CH; A

the formula Q "W CHalN wherein R is selected from the group consisting of hydrogen and radicals of the class consisting of lower alkyl, di- (lower alkyl)amino(lower alkylene),

Alk-N and (C H2) 1: (lower alkyl) and R is selected from the group consisting of lower alkyl and phenyl(lower alkylene), the step which comprises contacting a compound of the formula OH CH3 R wherein R is selected from the group consisting of lower alkyl and phenyl(lower alkylene), with formaldehyde.

References Cited by the Examiner UNITED STATES PATENTS 2,953,570 9/1960 Rudner 260569 2,957,873 10/ 1960 Rudner 2605 69 3,119,821 1/1964 Trepanier 260244 3,122,537 2/1964 Trepanier 260244 3,135,748 6/ 1964 Trepanier 260244 11/ 1964 Trepanier 260244 OTHER REFERENCES Fieser et al.: Organic Chemistry, 3rd Ed., pp. 237-9, Reinhold 1956).

Noller: Chemistry of Organic Compounds, 2nd Ed., pp. 241-242 (1957) (Saunders).

JOHN D. RANDOLPH,'Acting Primary Examiner.

IRVING MARCUS, NICHOLAS S. RIZZO, WALTER A. MODANCE, Examiners. 

1. A COMPOUND OF THE FORMULA
 12. D-N-AMINO - B - HYDROXY - N,A - DIMETHYLPHENETHYLAMINE.
 15. IN A PROCESS FOR THE PREPARATION OF A COMPOUND OF THE FORMULA 